Evaluation of silica from different vendors as the solid support of anion‐exchange chiral stationary phases by means of preferential sorption and liquid chromatography

Abstract

Chromatographic performance of a chiral stationary phase is significantly influenced by the employed solid support. Properties of the most commonly used support, silica particles, such as size and size distribution, and pore size are of utmost importance for both superficially porous particles and fully porous particles. In this work, we have focused on evaluation of fully porous particles from three different vendors as solid supports for a brush‐type chiral stationary phase based on 9‐O‐tert‐butylcarbamoyl quinidine. We have prepared corresponding stationary phases under identical experimental conditions and determined the parameters of the modified silica by physisorption measurements and scanning electron microscopy. Enantiorecognition properties of the chiral stationary phases have been studied using preferential sorption experiments. The same material was slurry‐packed into chromatographic columns and the chromatographic properties have been evaluated in liquid chromatography. We show that preferential sorption can provide valuable information about the influence of the pore size and total pore volume on the interaction of analytes of different size with the chirally‐modified silica surface. The data can be used to understand differences observed in chromatographic evaluation of the chiral stationary phases. The combination of preferential sorption and liquid chromatography separation can provide detailed information on new chiral stationary phases.

Synthesis by carbonate aminolysis and chiral recognition ability of cellulose 2,3-bis(3,5-dimethylphenyl carbamate)-6-(α-phenylethyl carbamate) selectors

“…Besides the chemical structure of the CS, the enantioseparation performance of a coated chiral stationary phase is significantly dependent on the polysaccharide raw material, its molecular weight (Ichida et al 1984;Chassaing et al 1997;Okada et al 2016;Zhang et al 2020), the coating amount, the coating procedure and solvent used (Yashima et al 1996;Wei et al 2019), as well as silica gel characteristics, such as particle size, dispersity, or pore size (Yashima et al 1996;Qin et al 2010;Bezhitashvili et al 2017;Kohout et al 2019), and of course the respective analytes, the mobile phase and HPLC conditions (Yashima et al 1996;Bui et al 2021). To ensure an objective comparison and proper evaluation of the enantioseparation performance of novel CSs, all parameters except the actual chemical structures of these CSs should of course be kept constant.…”

Optimization of the regioselective synthesis of mixed cellulose 3,5-dimethylphenyl and α-phenylethyl carbamate selectors as separation phases for chiral HPLC

“…Besides the substituents and their pattern, the enantioseparation performance of a certain CS significantly depends on the nature of the polysaccharide, its degree of polymerization (DP) (Okada et al 2016;Zhang et al 2020), the amount of selector coated onto the silica support, and the used coating/immobilization procedures (Yashima et al 1996;Wei et al 2019). Evidently, there is also an influence of the dimensions of the silica gel (Yashima et al 1996;Qin et al 2010;Bezhitashvili et al 2017;Kohout et al 2019), the analytes, and of course the HPLC conditions (Yashima et al 1996;Bui et al 2021) as it is also in non-chiral separations.…”